1. Field of the Invention
The present invention relates to a process for the wet-chemical treatment of workpieces, especially of semiconductor wafers, by exposing the workpieces to a flow of a gassified treatment medium.
2. The Prior Art
U.S. Pat. No. 5,014,727 discloses an apparatus with which semiconductor wafers can be washed. The semiconductor wafers are stacked in a supporting frame without touching one another. The supporting frame is immersed in a trough containing washing liquid. A pump pumps liquid overflowing from the trough back into the trough through the trough base via a filter, so that the semiconductor wafers are exposed to a flow of the liquid. Situated underneath the supporting frame on the trough base is a bubble generator with which gas bubbles are blown into the liquid for the purpose of mixing.
A disadvantage of this apparatus and the process which can be carried out therewith is that the distribution of the gas bubbles in the liquid is not homogeneous and therefore results in locally different flow conditions. The washing liquid consequently flows around the semiconductor wafers non-uniformly, and with varying intensity. This results in non-uniform treatment of the workpiece surfaces and an undesirable position-dependent success of the treatment, especially if, in addition to a cleaning action of the treatment, a material-removing etch treatment is provided by the liquid and/or the gas.